Semiconductor structure

ABSTRACT

A semiconductor structure includes a first capacitor and a second capacitor. The first capacitor includes a plurality of first units and each first unit includes a plurality of first finger electrodes. The second capacitor includes a plurality of second units and each second unit includes a plurality of second finger electrodes. The first units and the second units are alternately arranged to form an array. The semiconductor structure further includes a plurality of first connecting lines and a plurality of second connecting lines being parallel with each other. The first connecting lines are electrically connected to the first finger electrodes, and the second connecting lines are electrically connected to the second finger electrodes. The first finger electrodes and its adjacent first connecting lines form a straight line, and the second finger electrodes and its adjacent second connecting lines form another straight line.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of application Ser. No. 13/532,786filed Jun. 26, 2012, and included herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor structure, and moreparticularly, to a semiconductor capacitor structures with improvedmismatch performance.

2. Description of the Prior Art

In modern integrated circuits (ICs), capacitors are prevalently used.For example, in applications of analog devices, the capacitors usuallyused include the metal-insulator-metal (MIM) capacitor and themetal-oxide-metal (MOM) capacitor. Capacitances of the capacitors arevery sensitive to the fabrication process and structure design. And thecapacitors always suffer the capacitor mismatch issue, and thus accuracyof the resulting digital signals is adversely impacted.

Therefore, a capacitor structure with improved mismatch performance isstill in need.

SUMMARY OF THE INVENTION

According to an aspect of the present invention, a semiconductorstructure is provided. The semiconductor structure includes a firstcapacitor formed in a first layer, the first capacitor comprising aplurality of first units and each first unit further comprising aplurality of first finger electrodes; a second capacitor formed in thefirst layer, the second capacitor comprising a plurality of secondunits, the second units and the first units being alternately arrangedto form an array, and each second unit includes a plurality of secondfinger electrodes; a plurality of first connecting lines formed in thefirst layer, the first connecting lines being electrically connected tothe first finger electrodes, and the first finger electrodes and itsadjacent first connecting lines forming a straight line; and a pluralityof second connecting lines formed in the first layer, the secondconnecting lines being parallel with the first connecting lines andelectrically connected to the second finger electrodes, and the secondfinger electrodes and its adjacent second connecting lines forming astraight line.

According to another aspect of the present invention, a semiconductorstructure is provided. The semiconductor structure includes a pluralityof first finger electrodes formed in a first layer and a second layer; aplurality of second finger electrodes formed in the first layer and thesecond layer; a plurality of common finger electrodes formed in thefirst layer and the second layer, the common finger electrodes and thefirst finger electrodes being interdigitated to form a plurality offirst units in the first layer and the second layer, and the commonfinger electrodes and the second finger electrodes are interdigitated toform a plurality of second units in the first layer and the secondlayer; a plurality of first connecting lines formed in the first layer,the first connecting lines being electrically connected to two nearestfirst finger electrodes of different first units; and a plurality ofsecond connecting lines formed in the second layer, the secondconnecting lines being electrically connected to two nearest secondfinger electrodes of different second units, and the first connectinglines and the second connecting lines being parallel with each other.

According to the semiconductor structures provided by present invention,the connecting lines provided to electrically connect the fingerelectrodes are all parallel with each other, therefore the reliabilityof the capacitor is improved without adversely impacting the capacitormismatch.

These and other objectives of the present invention will no doubt becomeobvious to those of ordinary skill in the art after reading thefollowing detailed description of the preferred embodiment that isillustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-3 are schematic drawings illustrating a semiconductor structureprovided by a first preferred embodiment of the present invention.

FIG. 4 is a schematic drawing of a semiconductor structure provided by asecond preferred embodiment of the present invention.

FIGS. 5-7 are schematic drawings illustrating a semiconductor structureprovided by a third preferred embodiment of the present invention.

FIG. 8 is a schematic drawing of a semiconductor structure provided by afourth preferred embodiment of the present invention.

FIG. 9 is a schematic drawing of a semiconductor structure provided by afifth preferred embodiment of the present invention.

FIG. 10 is a schematic drawing of a semiconductor structure provided bya sixth preferred embodiment of the present invention.

FIG. 11 is a schematic drawing of a semiconductor structure provided bya seventh preferred embodiment of the present invention

FIGS. 12-13 are schematic drawings illustrating a semiconductorstructure provided by a eighth preferred embodiment of the presentinvention.

DETAILED DESCRIPTION

Please refer to FIGS. 1-3 which are schematic drawings illustrating asemiconductor structure provided by a first preferred embodiment of thepresent invention. As shown in FIG. 1, the first preferred embodimentprovides a first capacitor C₁ and a second capacitor C₂. The firstcapacitor C₁ includes a plurality of first units 100 and the secondcapacitor C₂ includes a plurality of second units 200, respectively.According to the preferred embodiment, an amount of the first units 100and an amount of the second units 200 are the same. In other words, anamount ratio between the first units 100 and the second units 200 isequal to 1. As shown in FIG. 1, each of the first units 100 includes aplurality of first finger electrodes 110 and a plurality of third fingerelectrodes 120, and the first finger electrodes 110 and the third fingerelectrodes 120 are interdigitated to form said first unit 100. In thesame concept, each of the second units 200 includes a plurality ofsecond finger electrodes 210 and a plurality of fourth finger electrodes220, and the second finger electrodes 210 and the fourth fingerelectrodes 220 are interdigitated to form said second unit 200.Furthermore, the first finger electrodes 110 in one first unit 100 areelectrically connected to each other by a first electrode 112 and thusobtains a comb shape. In the same concept, the third finger electrodes120 in one first unit 100 are electrically connected to each other by athird electrode 122 and thus obtains a comb shape, the second fingerelectrodes 210 in one second unit 200 are electrically connected to eachother by a second electrode 212 and thus obtains a comb shape, and thefourth finger electrodes 220 in one second unit 200 are electricallyconnected to each other by a fourth electrode 222 and thus obtains acomb shape. The first units 100 and the second units 200 are formed in afirst layer 10 and a second layer 20. In other words, the first fingerelectrodes 110 and the third finger electrodes 120 are positioned inboth of the first layer 10 and the second layer 20. In the same concept,the second finger electrodes 210 and the fourth finger electrodes 220are positioned in both of the first layer 10 and the second layer 20.The first layer 10 and the second layer can be, for example but notlimited to, a first layer (M1) and a second layer (M2) for themulti-layered metal interconnections in the back-end-of-line process.

Please still refer to FIG. 1. The first units 100 formed in the firstlayer 10 have an arrangement and locations the same with the first units100 formed in the second layer 20. Also, the second units 200 formed inthe first layer 10 have an arrangement and locations the same with thesecond units 200 formed in the second layer 20. It is noteworthy thatthe first units 100 and the second units 200 formed in the first layer10 are alternately arranged to form an array and so are the first units100 and the second units 200 formed in the second layer 20. As shown inFIG. 1, the array formed by the first units 100 and the second units 200includes a plurality of columns and row. It should be noted that centralpoints of the first units 100 and central points of the second units 200in the same row form a piecewise linear line, and central points of thefirst units 100 and central points of the second units 200 in the samecolumn form a piecewise linear line as shown in FIG. 1. Furthermore, thefirst finger electrodes 110 and the third finger electrodes 120 of thefirst units 100 arranged in the adjacent rows have different arrangementorder. For example, in the first units 100 formed in the odd-row, thearrangement order of the first finger electrodes 110 and the thirdfinger electrodes 120 is: the third finger electrode 120-the firstfinger electrode 110-the third finger electrode 120-the first fingerelectrode 110 . . . -the third finger electrode 120-the first fingerelectrode 110. However, in the first units 100 formed in the even-row,the arrangement order of the first finger electrodes 110 and the thirdfinger electrodes 120 is: the first finger electrode 110-the thirdfinger electrode 120-the first finger electrode 110-the third fingerelectrode 120 . . . -the first finger electrode 110-the third fingerelectrode 120. In the same concept, the second finger electrodes 210 andthe fourth finger electrodes 220 of the second units 200 arranged in theadjacent rows have different arrangement order. For example, in thesecond units 200 formed in the odd-row, the arrangement order of thesecond finger electrodes 210 and the fourth finger electrodes 220 is:the second finger electrode 210-the fourth finger electrode 220-thesecond finger electrode 210-the fourth finger electrode 220- . . . -thesecond finger electrode 210-the fourth finger electrode 220. However inthe second units 200 formed in the even-rows, the arrangement order ofthe second finger electrodes 210 and the fourth finger electrodes 220is: the fourth finger electrode 220-the second finger electrode 210-thefourth finger electrode 220-the second finger electrode 210 . . . -thefourth finger electrode 220-the second finger electrode 210.

Please refer to FIG. 2. The semiconductor structure provided by thepreferred embodiment further includes a plurality of first connectinglines 130 formed in the first layer 10. The first connecting lines 130are electrically connected to the first finger electrodes 110. In otherwords, the first finger electrodes 110 are electrically connected toeach other by the first electrodes 112 and the first connecting lines130. More important, the first finger electrodes 110 and its adjacentfirst connecting lines 130 are parallel with each other and further forma straight line as shown in FIG. 2. It is noteworthy that by connectingthe first finger electrodes 110 through the first connecting lines 130,the first units 100 in adjacent rows are electrically connected.Additionally, the electrically connected first units 100 are alternatelyarranged along the first connecting lines 130 like alternate leaves.Also, the semiconductor structure provided by the preferred embodimentincludes a plurality of second connecting lines 230 formed in the firstlayer 10. The second connecting lines 230 are electrically connected tothe second finger electrodes 210. In other words, the second fingerelectrodes 210 are electrically connected to each other by the secondelectrodes 212 and the second connecting lines 230. More important, thesecond finger electrodes 210 and its adjacent second connecting lines230 are parallel with each other and further form a straight line asshown in FIG. 2. By connecting the second finger electrodes 210 throughthe second connecting lines 230, the second units 200 in adjacent rowsare electrically connected. Additionally, the electrically connectedsecond units 200 are alternately arranged along the second connectinglines 230 like alternate leaves. More important, the first connectinglines 130 and the second connecting lines 230 are parallel with eachother as shown in FIG. 2.

Please refer to FIG. 3. The semiconductor structure provided by thepreferred embodiment further includes a plurality of third connectinglines 132 formed in the second layer 20. The third connecting lines 132are perpendicular to the third finger electrodes 120. By connecting thethird electrodes 122, which electrically connected to the third fingerelectrodes 120, and the third connecting lines 132, the first units 100in adjacent columns are electrically connected. In other words, thethird finger electrodes 120 are electrically connected to each other bythird electrodes 122 and the third connecting lines 132. Additionally,the electrically connected first units 100 are alternately arrangedalong the third connecting lines 132 like alternate leaves. Also, thesemiconductor structure of the preferred embodiment includes a pluralityof fourth connecting lines 232 formed in the second layer 20. The fourthconnecting lines 232 are perpendicular to the fourth finger electrodes220. By connecting the fourth electrodes 222, which electricallyconnected to the fourth finger electrodes 220, and the fourth connectinglines 232, the second units 200 in adjacent columns are electricallyconnected. In other words, the fourth finger electrodes 220 areelectrically connected to each other by the fourth electrodes 222 andthe fourth connecting lines 232. Additionally, the electricallyconnected second units 200 are alternately arranged along the fourthconnecting lines 232 like alternate leaves. More important, the thirdconnecting lines 132 and the fourth connecting lines 232 are parallelwith each other as shown in FIG. 3.

According to the semiconductor structure provided by the first preferredembodiment, the connecting lines that used to electrically connect thecapacitor units 100/200 are parallel with or perpendicular to the fingerelectrodes and thus are different from the prior art, in which theconnecting lines used to electrically connect capacitor units areneither parallel with, nor perpendicular to the finger electrodes. Infact, the connecting lines and the finger electrodes often have anincluded angle of 45° in the prior art. Accordingly, the adverse impactrendered from the non-parallel and non-perpendicular designs for theconnecting lines and the finger electrodes are avoided by thesemiconductor structure provided by the preferred embodiment.

Additionally, the semiconductor structure provided by the firstpreferred embodiment includes four terminals (not shown), for example afirst positive terminal C₁+ of the first capacitor C₁ in the first layer10, a second positive terminal C₂+ of the second capacitor C₂ in thefirst layer 10, a first negative terminal C₁− of the first capacitor C₁in the second layer 20, and a second negative terminal C₂− of the secondcapacitor C₂ in the second layer 20. As mentioned above, the firstfinger electrodes 110 are electrically connected to each other, and thefirst finger electrodes 110 are further electrically connected to thefirst positive terminal C₁+. In the same concept, the third fingerelectrodes 120 are electrically connected to each other and furtherelectrically connected to the first negative terminal C₁−, the secondfinger electrodes 210 are electrically connected to each other andfurther electrically connected to the second positive terminal C₂+, andthe fourth finger electrodes 220 are electrically connected to eachother and further electrically connected to the second negative terminalC₂−.

Please refer to FIG. 4, which is a schematic drawing of a semiconductorstructure provided by a second preferred embodiment of the presentinvention. It is noteworthy that elements the same in both of the firstpreferred embodiment and the second preferred embodiment are designatedby the same numerals and the details are omitted herein in the interestof brevity. Furthermore, FIG. 4 illustrates the first capacitor C₁andthe second capacitor C₂ formed in both of the first layer 10 and thesecond layer 20. According to the first preferred embodiment, a spacingdistance d₁ between the first units 100 and the second connecting lines230, and between first units 100 and the fourth connecting lines 232 areequal to or smaller than 0.6 micrometer (μm). A spacing distance d₂between the second units 200 and the first connecting lines 130, andbetween the second units 200 and the third connecting lines 132 are alsoequal to or smaller than 0.6 μm. Different from the first preferredembodiment, the semiconductor structure provided by the second preferredembodiment includes a spacing distance d₁ between the first units 100and the second connecting lines 230 and between the first units 100 andthe fourth connecting lines 232, and the spacing distance d₁ is between0.6 μm and 0.8 μm. In the same concept, a spacing distance d₂ betweenthe second units 200 and the first connecting lines 130 and between thesecond units 200 and the third connecting lines 132 is also between 0.6μm and 0.8 μm. In other words, the spacing distances d₁/d₂ betweencapacitor units 100/200 and adjacent capacitor units 200/100 areincreased.

According to the semiconductor structure provided by the secondpreferred embodiment, coupling capacitance between different capacitorunits 100/200 is reduced by increasing the spacing distances d₁/d₂, andthus capacitive crosstalk between different capacitor units 100/200 ismitigated.

Please refer to FIGS. 5-7, which are schematic drawings illustrating asemiconductor structure provided by a third preferred embodiment of thepresent invention. It is noteworthy that elements the same in theabovementioned preferred embodiments and the third preferred embodimentare designated by the same numerals and the details are omitted hereinin the interest of brevity. It should be noted that the spacingdistances d₁/d₂ between the capacitor units 100/200 and adjacentcapacitor units 200/100 can be increased to between 0.6 μm and 0.8 μm asdescribed in the second preferred embodiment. The differences betweenthe second preferred embodiment and the third preferred embodiment is: aplurality of guarding rings 30 are positioned in between the adjacentfirst units 100 and second units 200 in each row in the first layer 10as shown in FIG. 5. Furthermore, a plurality of guarding rings 32 isselectively positioned in between the adjacent first units 100 andsecond units 200 in each column in the second layer 20 as shown in FIG.6. As shown in FIG. 5 and FIG. 6, an extending direction of the guardingrings 30 in the first layer 10 is the same with extending directions ofthe first connecting lines 130 and the second connecting lines 230. Andan extending direction of the guarding rings 32 in the second layer 20is the same with extending directions of the third connecting lines 132and the fourth connecting lines 232. The guarding rings 30/32 positionedin the layers 10/20 are electrically connected by plugs 34, and furthergrounded by the plugs 34 as shown in FIG. 7. Consequently, the capacitorunits 100/200 are shielded by the guarding rings 30/32 and thus couplingcapacitance is further reduced.

According to the semiconductor structure provided by the third preferredembodiment, coupling capacitance and capacitive crosstalk between thecapacitor units 100/200 are all reduced by increasing spacing distanced₁/d₂ between the capacitor units 100/200 and its adjacent capacitorunits 200/100 and by positioning the guarding rings 30/32.

Please refer to FIG. 8, which is a schematic drawing of a semiconductorstructure provided by a fourth preferred embodiment of the presentinvention. It is noteworthy that elements the same in the aforementionedpreferred embodiments and the fourth preferred embodiment are designatedby the same numerals and the details are omitted herein in the interestof brevity. It should be noted that the semiconductor structure shown inFIG. 8 is resulted from overlapping the first layer 10 and the secondlayer 20. As shown in FIG. 8, the semiconductor structure provided bythe preferred embodiment includes a first capacitor C₁ and a secondcapacitor C₂. The first capacitor C₁ includes a plurality of first units100 and the second capacitor C₂ includes a plurality of second units200.

As shown in FIG. 8, each of the first units 100 includes a plurality offirst finger electrodes 110 and a plurality of third finger electrodes120, and the first finger electrodes 110 and the third finger electrodes120 are interdigitated to form said first unit 100. In the same concept,each of the second units 200 includes a plurality of second fingerelectrodes 210 and a plurality of fourth finger electrodes 220, and thesecond finger electrodes 210 and the fourth finger electrodes 220 areinterdigitated to form said second unit 200. Furthermore, the firstfinger electrodes 110 in one first unit 100 are electrically connectedto each other by a first electrode 112 and thus obtains a comb shape. Inthe same concept, the third finger electrodes 120 in one first unit 100are electrically connected to each other by a third electrode 122 andthus obtains a comb shape, the second finger electrodes 210 in onesecond unit 200 are electrically connected to each other by a secondelectrode 212 and thus obtains a comb shape, and the fourth fingerelectrodes 220 in one second unit 200 are electrically connected to eachother by a fourth electrode 222 and thus obtains a comb shape.

Please still refer to FIG. 8. The semiconductor structure provided bythe preferred embodiment further includes a plurality of firstconnecting lines 130 formed in the first layer 10. The first connectinglines 130 are electrically connected to the first finger electrodes 110.More important, the first finger electrodes 110 and its adjacent firstconnecting lines 130 are parallel with each other and further form astraight line as shown in FIG. 8. The semiconductor structure alsoincludes a plurality of second connecting lines 230 formed in the firstlayer 10. The second connecting lines 230 are electrically connected tothe second finger electrodes 210. And the second finger electrodes 210and its adjacent second connecting lines 230 are parallel with eachother and further form a straight line as shown in FIG. 8. Moreimportant, the first connecting lines 130 and the second connectinglines 230 are parallel with each other as shown in FIG. 8.

Please refer to FIG. 8. The semiconductor structure provided by thepreferred embodiment further includes a plurality of third connectinglines 132 formed in the second layer 20. The third connecting lines 132are electrically connected to the third electrode 122 and thuselectrically connected to the third finger electrodes 120. According tothe preferred embodiment, the third connecting lines 132 areperpendicular to the third finger electrodes 120. Also, thesemiconductor structure includes a plurality of fourth connecting lines232 formed in the second layer 20. The fourth connecting lines 232 areelectrically connected to the fourth electrode 222 and thus electricallyconnected to the fourth finger electrodes 220. According to thepreferred embodiment, the fourth connecting lines 232 are alsoperpendicular to the fourth finger electrodes 220. As shown in FIG. 8,the third connecting lines 132 and the fourth connecting lines 232 areparallel with each other.

It is noteworthy that according to the preferred embodiment, an amountof the first units 100 and an amount of the second units 200 aredifferent. In other words, the semiconductor structure of the preferredembodiment includes an amount ratio between the first units 100 and thesecond units 200, and the amount ratio is larger than 1. As shown inFIG. 8, the amount ratio between the first units 100 and the secondunits 200 is 3 in the preferred embodiment. However, the amount ratiobetween the first units 100 and the second units 200 can be 5 or 7, butnot limited to this.

In addition, coupling capacitance and capacitive crosstalk between thecapacitor units 100/200 can be reduced by increasing spacing distanced₁/d₂ (not shown) between the capacitor units 100/200 and its adjacentcapacitor units 200/100 and by positioning the guarding rings 30/32.

According to the semiconductor structure provided by the fourthpreferred embodiment, the first capacitor C₁ and the second capacitor C₂can obtain different capacitances by modifying the amount of the firstunits 100 and the amount of the second units 200. In other words, byproviding different wiring patterns, different capacitances can berealized and thus satisfies with different capacitance requirements ofICs.

Please refer to FIG. 9, which is a schematic drawing of a semiconductorstructure provided by a fifth preferred embodiment of the presentinvention. As shown in FIG. 9, the fifth preferred embodiment provides afirst capacitor C₁ and a second capacitor C₂. The first capacitor C₁includes a plurality of first units 300 and the second capacitor C₂includes a plurality of second units 400. According to the preferredembodiment, an amount of the first units 300 is the same with an amountof the second units 400. In other words, an amount ratio between thefirst units 300 and the second units 400 is 1. As shown in FIG. 9, eachof the first units 300 includes a plurality of first finger electrodes310 and each of the second units 400 includes a plurality of secondfinger electrodes 410. The first finger electrodes 310 in one first unit300 are electrically connected to each other by a first electrode 312and thus obtains a comb shape. In the same concept, the second fingerelectrodes 410 in one second unit 400 are electrically connected to eachother by a second electrode 412 and thus obtains a comb shape. The firstunits 300 and the second units 400 are formed in a first layer 12. Inother words, the first finger electrodes 310 and the second fingerelectrodes 410 are formed in the first layer 12. It is noteworthy thataccording to the preferred embodiment, the semiconductor structurefurther includes a plurality of common finger electrodes 500 formed inthe first layer 12. The common finger electrodes 500 include a fishboneshape. As shown in FIG. 9, the common finger electrodes 500 and thefirst finger electrodes 310 are interdigitated to form the first units300, while the common finger electrodes 500 and the second fingerelectrodes 410 are also interdigitated to form the second units 400. Asshown in FIG. 9, the first units 300 and the second units 400 formed inthe first layer 12 are alternately arranged to form an array, and thearray includes a plurality of columns and a plurality of rows. Moreimportant, central points of the first units 300 and central points ofthe second units 400 in the same row form a piecewise linear line asshown in FIG. 9.

Please still refer to FIG. 9. The semiconductor structure provided bythe preferred embodiment further includes a plurality of firstconnecting lines 330 formed in the first layer 12. The first connectinglines 330 are electrically connected to the first finger electrodes 310.In other words, the first finger electrodes 310 are electricallyconnected to each other by the first electrodes 312 and the firstconnecting layer 330. More important, the first finger electrodes 310and its adjacent first connecting lines 330 are parallel with each otherand further form a straight line as shown in FIG. 9. It is noteworthythat by connecting the first finger electrodes 310 through the firstconnecting lines 330, the first units 300 in the same row areelectrically connected. Also, the semiconductor structure of thepreferred embodiment includes a plurality of second connecting lines 430formed in the first layer 12. The second connecting lines 430 areelectrically connected to the second finger electrodes 410. In otherwords, the second finger electrodes 430 are electrically connected toeach other by the second connecting layer 430. The second fingerelectrodes 410 and its adjacent second connecting lines 430 are parallelwith each and further form a straight line as shown in FIG. 9. Byconnecting the second finger electrodes 410 through the secondconnecting lines 430, the second units 400 in the same row areelectrically connected. More important, the first connecting lines 330and the second connecting lines 430 are parallel with each other asshown in FIG. 9.

According to the semiconductor structure provided by the preferredembodiment, the capacitor units 300/400 are all formed in one layer 12instead of two layers by forming the common finger electrodes 500. Thusthe fabricating process is simplified. However, the first electrode 412,the second electrode 512, and the common finger electrodes 500 still canbe formed in two layers if required. Furthermore, by forming via plugsrespectively in the first electrode 412, the second electrode 512, andthe fishbone-shaped common finger electrodes 500, the first units 300and the second units 400 in two layers are electrically connected andthus the first capacitor C₁ and the second capacitor C₂ are stillobtained.

Additionally, the semiconductor structure provided by the fifthpreferred embodiment includes four terminals (not shown), for example afirst positive terminal C₁+ of the first capacitor C₁, a second positiveterminal C₂+ of the second capacitor C₂, and a common negative terminalC− in the first layer 12. As mentioned above, the first fingerelectrodes 310 are electrically connected to each other, and the firstfinger electrodes 310 are further electrically connected to the firstpositive terminal C₁+. In the same concept, the second finger electrodes410 are electrically connected to each other and further electricallyconnected to the second positive terminal C₂+, and the common fingerelectrodes 500 are electrically connected to each other and furtherelectrically connected to the common negative terminal C−.

Please refer to FIGS. 10-11, wherein FIG. 10 is a schematic drawing of asemiconductor structure provided by a sixth preferred embodiment of thepresent invention and FIG. 11 is a schematic drawing of a semiconductorstructure provided by a seventh preferred embodiment of the presentinvention. To understand the differences between the sixth preferredembodiment and the seventh preferred embodiment, it is more preferableto refer to FIG. 10 and FIG. 11 simultaneously. Additionally, elementsthe same in the fifth, the sixth and the seventh preferred embodimentsare designated by the same numerals and the same details are omitted forsimplicity.

The differences between the fifth and the sixth preferred embodimentsis: the first finger electrodes 310 are electrically connected to eachother by the first electrode 312 and thus obtain the comb shape whilethe second finger electrodes 410 are electrically connected to eachother by the second electrode 412 and thus obtain the comb shape in thefifth preferred embodiment. Differently, the first finger electrodes 310are electrically connected to each other by the first electrode 312 andto obtain a fishbone shape while the second finger electrodes 410 areelectrically connected to each other by the second electrode 412 and toobtain a fishbone shape according to the sixth preferred embodiment. Thefirst electrode 312 serves as the spine which electrically connects thefirst finger electrodes 310, and the second electrode 412 serves as thespine which electrically connects the second finger electrodes 410.Between the first finger electrodes 310 and the second finger electrodes410, the fishbone-shaped common finger electrodes 500 are positioned.According to the preferred embodiment, an amount of the first fingerelectrodes 310 is the same with an amount of the second fingerelectrodes 410. In other words, a capacitances ratio between the firstcapacitor C₁ and the second capacitor C₂ is 1.

Please refer to FIG. 11. The difference between the seventh preferredembodiment and the sixth preferred embodiment is: the amount of thefirst finger electrodes 310 is different from the amount of the secondfinger electrodes 410. As shown in FIG. 11, in the same column, anamount ratio between the first finger electrodes 310 and the secondfinger electrodes 410 is 3:2. In other words, an amount ratio betweenthe first finger electrodes 310 and the second finger electrodes 410 islarger than 1.

According to the sixth and seventh preferred embodiments, the capacitorunits 300/400 are all formed in one layer 12 instead of two layers byforming the common finger electrodes 500. Thus the fabricating processis simplified. Furthermore, by modifying the amount of the first fingerelectrodes 310 and the amount of the second finger electrodes 410, thefirst capacitor C₁ and the second capacitor C₂ obtain differentcapacitances. In other words, by providing different wiring patterns,different capacitances can be realized and thus satisfies with differentcapacitance requirements of ICs.

Please refer to FIGS. 12-13, which are schematic drawings illustrating asemiconductor structure provided by an eighth preferred embodiment ofthe present invention. As shown in FIGS. 12-13, the semiconductorstructure provided by the preferred embodiment includes a plurality offirst finger electrodes 710, a plurality of second finger electrodes810, and a plurality of common finger electrodes 900 formed in a firstlayer 14 and a second layer 24. The first finger electrodes 710 areelectrically connected to each other by a first electrode 712 and thusobtain a comb shape. In the same concept, the second finger electrodes810 are electrically connected to each other by a second electrode 812and thus obtain a comb shape, too. As shown in FIGS. 12-13, the commonfinger electrodes 900 and the first finger electrodes 710 areinterdigitated to form a plurality of first units 700 in both of thefirst layer 14 and the second layer 24. The common finger electrodes 900and the second finger electrodes 810 are also interdigitated to form aplurality of second units 800 in both of the first layer 14 and thesecond layer 24. It is noteworthy that the first units 700 formed in thefirst layer 14 and the second layer 24 have a same arrangement andlocations, and the second units 800 formed in the first layer 14 and thesecond layer 24 have a same arrangement and locations, too. Furthermore,the first units 700 and the second units 800 formed in the first layer14 are alternately arranged to form an array. The first units 700 andthe second units 800 formed in the second layer 24 are also arranged toform an array. For example, the first units 700 in the first layer 14and the second layer 24 are always adjacent to one of the second units800. In other words, the first units 700 are diagonally arranged. In thesame concept, the second units 800 in the first layer 14 and the secondlayer 24 are always adjacent to one of the first units. In other words,the second units 800 are diagonally arranged.

According to the preferred embodiment, a plurality of first via plugs714, a plurality of second via plugs 814, and a plurality of third viaplugs 914 (all shown in FIG. 13) are provided. The first via plugs 714are used to electrically connect the first finger electrodes 710 formedin the first layer 14 and the second layer 24. The second via plugs 814are used to electrically connect the second finger electrodes 810 formedin the first layer 14 and the second layer 24. And the third via plugs914 are used to electrically connect the common finger electrodes 900formed in the first layer 14 and the second layer 24. Therefore, thefirst units 700 in the first layer 14 and the second layer 24 are allelectrically connected to form a first capacitor C₁, and the secondunits 800 in the first layer 14 and the second layer 24 are all areelectrically connected to form a second capacitor C₂.

Please still refer to FIG. 12 and FIG. 13. The semiconductor structureprovided by the preferred embodiment further includes a plurality offirst connecting lines 730 formed in the first layer 14. The firstconnecting line 730 is used to electrically connect two nearest firstfinger electrodes 710 of different first units 700. The semiconductorstructure provided by the preferred embodiment further includes aplurality of second connecting lines 830 formed in the second layer 24.The second connecting line 830 is used to electrically connect twonearest second finger electrodes 810 of different second units 800. Itis noteworthy that the first connecting lines 730 are perpendicular tothe first finger electrodes 710 and the second connecting lines 830 areperpendicular to the second finger electrodes 810. More important, thefirst connecting lines 730 formed in the first layer 14 are parallelwith the second connecting lines 830 formed in the second layer 24.

According to the semiconductor structure provided by the preferredembodiment, the connecting lines that used to electrically connect thecapacitor units 700/800 are parallel with or perpendicular to the fingerelectrodes and thus are different from the prior art, in which theconnecting lines used to connect capacitor units are neither parallelwith, nor perpendicular to the finger electrodes. In fact, theconnecting lines and the finger electrodes often have an included angleof 45° in the prior art. Accordingly, the adverse impact rendered fromthe non-parallel and non-perpendicular designs for the connecting linesand the finger electrodes are avoided by the semiconductor structureprovided by the preferred embodiment.

According to the semiconductor structures provided by present invention,the connecting lines used to electrically connect the finger electrodesare all parallel with each other, therefore the reliability of thecapacitor is improved without adversely impacting the capacitormismatch.

Those skilled in the art will readily observe that numerousmodifications and alterations of the device and method may be made whileretaining the teachings of the invention. Accordingly, the abovedisclosure should be construed as limited only by the metes and boundsof the appended claims.

What is claimed is:
 1. A semiconductor structure comprising: a pluralityof first finger electrodes formed in a first layer and a second layer; aplurality of second finger electrodes formed in the first layer and thesecond layer; a plurality of common finger electrodes formed in thefirst layer and the second layer, the common finger electrodes and thefirst finger electrodes being interdigitated to form a plurality offirst units in the first layer and the second layer, and the commonfinger electrodes and the second finger electrodes being interdigitatedto form a plurality of second units in the first layer and the secondlayer; a plurality of first connecting lines formed in the first layer,the first connecting lines being electrically connected to two nearestfirst finger electrodes of different first units; and a plurality ofsecond connecting lines formed in the second layer, the secondconnecting lines being electrically connected to two nearest secondfinger electrodes of different second units, and the first connectinglines and the second connecting lines being parallel with each other. 2.The semiconductor structure according to claim 1, wherein the firstunits and the second units are alternately arranged to form an array. 3.The semiconductor structure according to claim 1, wherein the firstunits formed in the first layer and the second layer are electricallyconnected to form a first capacitor, and the second units formed in thefirst layer and the second layer are electrically connected to form asecond capacitor.
 4. The semiconductor structure according to claim 1further comprising: a plurality of first via plugs electricallyconnected to the first finger electrodes formed in the first layer andthe second layer; a plurality of second via plugs electrically connectedto the second finger electrodes formed in the first layer and the secondlayer; and a plurality of third via plugs electrically connected to thecommon finger electrodes formed in the first layer and the second layer.